[php-src] PR #23930: fibers: fix GH-23921 (Fibers start with error_reporting = 0 when the error_reporting INI directive is not set)

Pull Request: https://github.com/php/php-src/pull/23930 Author: Girgias The way zend_fiber_execute() was querying the error reporting was rather strange, as it didn't rely on the value of EG(error_reporting). This was done as the @ silence operator could leak inside the body of fibers, however this situation can be detected more simply if the value of EG(error_reporting) and the value of the INI setting differ. I'm not *fully* confident this is the correct fix but the only test that fails if we don't query the INI setting is Zend/tests/fibers/silence-operator-outside-fiber.phpt. Note: the new test always succeeded as the test runner (I think) has a default INI setting.